A sampling scheme to generate pulse width modulated (PWM) signals may include a comparator to compare an input signal with a triangular waveform. The design of such a comparator in a fully differential manner can be difficult. First, a fully differential comparator may utilize two input terminals and two reference inputs for the differential reference. The input stage may be arranged as a differential differencing amplifier. Further, an input common mode of the circuit may be from rail-to-rail. These constraints can adversely affect the speed and accuracy of the comparator.
Further, a digital subscriber line (DSL) line driver at a central office (CO) may be implemented as a bipolar class-AB amplifier. However, linear amplification of a discrete multi tone (DMT) signal may be very power inefficient because the signal hovers around zero with occasional peaks due to the large peak-to-root mean square (rms) ratio (PAR).